Numerical simulation of the spectral development of inviscid helical flows

We have studied numerically the time development of the energy spectrum of inviscid, incompressible, helical flows. It is well known that helicity delays the development of turbulence. The aim of this paper is to study this phenomenon in more detail by investigating the influence of the number of modes in the initial flow field on the spectral development. We studied the cases with one, two, three or twenty-four modes with and without helicity in the initial flow field. It is found that the delay in the spectral development due to helicity is strongly dependent on the number of initial modes. The delay increases with decreasing number of modes. For the case of one initial mode with maximum helicity no development of the energy spectrum occurs. However, for the case of twenty-four initial modes with maximum helicity, energy transfer between the modes takes place without much delay when compared to the case of twenty-four initial modes without helicity. (C) 2011 Elsevier Masson SAS. All rights reserved.